Passive Solar Buildings

General description

A passive solar building is one that derives a substantial fraction of its heat from the sun using only natural processes to provide the necessary energy flows. Thermal conduction, free convection, and radiation transport therefore replace the pumps, blowers, and controllers associated with active solar heating systems. The elements of a passive solar heating system tend to be closely integrated with the structure for which heat is provided. South facing windows, for example, may serve as apertures through which solar energy is admitted to the building, and thermal storage may be provided by inherent structural mass.

Solar radiation absorbed inside the building is converted to heat, part of which meets the current heat load whereas the remainder is stored in the structural mass for later use after the sun has set. Because of the integral nature of passive solar buildings, it is not possible to design the structure independent of the heating system as is usually done with active systems. Instead, it is necessary to consider the solar characteristics of the building from the initial phases of the design process to completion of the construction documents.

A well designed passive solar building is comfortable, energy efficient, and very reliable because of its inherent operational simplicity. However, a poor design, lacking some or all of these desirable characteristics, may be very difficult to modify after construction is complete and the problems become manifest. It has therefore been necessary to develop a new approach to building design that couples solar/thermal considerations with the more traditional concerns of form and structure.

Purpose of the design procedures

The purpose of these procedures is to make the results of recent scientific research on passive solar energy accessible to professionals involved in building design or design evaluation. By so doing, this new technology can be transferred from the research laboratory to the drawing board and the construction site. A successful transfer will undoubtedly improve the energy efficiency of new buildings as well as many existing buildings that are suitable for retrofit.

This document is addressed principally to prospective Navy contractors for design and construction of passive solar buildings. However, because good passive solar designs are of little value if they are rejected in favor of more conventional but less efficient structures, the design analysis procedures presented herein are also intended for use by engineers and architects involved in the evaluation process. The calculations that are involved are based on the use of simple tables and graphs. An arithmetical calculator is the only tool required.